No youre right, it has no meaning to discuss the precision, I just accidently sidetracked this a bit with prj.

My meaning was to say why the fvisrm_w is calculated with 10.13 instead of the regular 1013, is to put less strain in the algorithm. If you look further at the calculation of ps_w it is crystal clear, there are further computions.  

You could have 1013 there instead of 10.13 and it would work anyway, youll just end up with two decimals higher values in KFURL/PRG and there is where more important precision would be lost.

More fuel for thought.

The pull below is 2nd gear one which resulted in leaning out up top drastically due to PS_W dropping inexplicably at normal maf flow and boost level readouts. PS_W drops in 0.1s from 3320 to 2673 (and so does engine load), that's 20% drop all of the sudden. My Zeitronix AFR ("WB_AFR_b1" or "WB_Lambda_b1") reports corresponding increase in AFR as the PS_W dips and interestingly, msdk_w (air flow over throttle) bumps up at the same cell by 1.6x from previous one.

This is with newly reset KISRM to stock value. I didn't see that in previous logs with halved KISRM.

It seems like PS_W calculation is fubarred now with stock KISRM given that everything else seems normal for a pull... how is everyone else with stock KISRM?

Doesn't it? Except that I don't see MAF flow change which usually is a result of switching cams off (you can see a notch) and that my changeover is at 4k. I will log the same with KISRM halved next to ensure I have no other issues.

Sat down and looked through all the code, as the docs really do not state clearly how this actually works.

ps_w at startup is initialized to pu_w.
After that ps_w is never completely re-assigned. Basically what happens is, delta manifold pressure is calculated and then added to ps_w.

It subtracts rl_w from rlroh_w to get the delta between current load and load from MAF and this delta is multiplied by fvisrm_w, which is (KISRM * ftsr).
If it is not zero, it is either added or subtracted from ps_w, and we get the new ps_w value. Basically fvisrm_w is conversion from load into pressure (opposite of KFURL).

After that ps_w is converted to load via KFURL, however KFURL itself does not affect ps_w directly.

So what happens if you do not halve KISRM nor the 10.13 calculation?
Your delta pressure is evaluated to double, and the filling models in the ECU start fighting each other.
I looked at this a long time ago, and came to the conclusion that KISRM or the 10.13 must be halved. Looked at this again now with a fresh start, and came to exact the same conclusion.

Thank you, now with your new understanding we can discuss how this works


No, it is not a conversion and not the opposite of KFURL. It is an Integrator (KISRM = Konstant Integrator saugrohrmodel), and one thing that the FR actually states in all this, is KISRM's function.

It also states how to turn the function off(KISRM = 1), if KISRM really was where we scaled ps_w this would net you a modeled intake pressure of 20-30bar lol. Julex log also prooves this, he doubled his KISRM but he didnt end up with a ps_w of 6000hPa.

KISRM is there to tune the response of ps_w, just like any other I part.


I agree, KFURL controls ps_w indirectly(with offset of KFPRG).


The fvisrm_w mulu is applied to the load delta before we scale down ps_w.

Edit: I have to get back on that one tbh

So youre still holding on to this?

Hiccups are still there with halved KISRM. I am getting mysterious PS_W drop with associated RL_W and fueling going awry per my wideband O2 although ECU things everything is ok, of course. NWS switchover is at 4k and I see associated activity so I don't think this is the culprit, but here is the KFURL as requested.

Please look at my log, row 88 and 89. PS_W drops again and so does RL_W... I will welcome any suggestions.

Edit: I will log pvdkds_w to see if I am not hitting psmx_w (I don't have memory address for psmx_w, but pvdkds_w will suffice) and therefore limit the ps_w.